Resum:

In this PhD dissertation, set within the analytic tradition of the contemporary philosophy of language, I take on some of the most debated issues concerning the semantics of natural language conditionals. I strive to give a plausible account of their meaning, which would not only ward off the classical puzzles (paradoxes of the material and strict conditional, Goodman's and Tichý's problems, differences between indicatives and subjunctives, etc.), but also explain why they arise in the first place.
I argue that truth-conditional approaches to meaning are often based on unwarranted implicit assumptions and tend to favour semantic reductionism. Yet there is no reason for us to expect that some of our most sophisticated expressions should be logically reducible to any purportedly more basic vocabulary. And indeed, many attempts at a truth-conditional analysis of conditional clauses have turned out to be blatantly vacuous.
A more natural way to explain the meaning of conditionals is to point out the function they carry out in standard language exchanges. Approached from this perspective, indicative conditional clauses are arguably best viewed as devices limiting the validity of the speech act performed by the main clause. This offers us a handle on both the paradoxes of the material conditional and its usefulness in mathematics, as well as a range of other phenomena, such as the so-called biscuit conditionals and quantification restriction.
Subjunctive conditionals, on the other hand, make simple assertions about the inferential potential of the hypotheses introduced by their antecedents, given a well-defined inferential scenario. I argue that our picture of the world provides such a scenario---there are few bare facts, as almost all that we know about the reality is organised in (roughly causal) patterns. It is these patterns that support our everyday assertions of counterfactuals.